About the Cover
On the Cover: Salt cress (Thellungiella halophila) is a small winter annual crucifer with a short life cycle. Native to harsh environments, salt cress has a small genome (about 2 Arabidopsis), possesses high sequence identity with Arabidopsis, and can be genetically transformed by the floral dip procedure. Salt cress is capable of copious seed production, as illustrated in the cover image of various stages of salt cress development. In this issue, Inan et al. (pp. 1718Ð1737) and Taji et al. (pp. 1697Ð1709) demonstrate that salt cress is an extremophile that can reproduce after exposure to extreme salinity (500 mM NaCl) or low temperature ( -15° C). It accumulates NaCl as well as high levels of Pro (>150 mM) during exposure to high salinity. It exhibits all the physiological, biochemical, and genetic traits of a hapophyte, and it demonstrates exceptional tolerance to salt- and low-temperature stress. Importantly, the species possesses characteristics that allow it to serve as a genetic model for understanding the extraordinary mechanisms of tolerance that exist in some plant families. Several EMS mutants of salt cress exhibit reduced salinity tolerance and provide evidence that salt tolerance in this hapophyte can be significantly affected by individual genetic loci. Analysis of salt cress ESTs provides evidence for the presence of paralogs, missing in the Arabidopsis genome, and for genes with abiotic stress-relevant functions. Efficient transformation of salt cress allows for simple gene exchange between Arabidopsis and salt cress, and the generation of T-DNA tagged mutant collections of salt cress, currently in progress, will facilitate forward and reverse genetic studies. Salt cress represents the beginning of a set of ARMS growing out of the Arabidopsis model system body. Photo by Robert Joly and Claudia Boccongeli.
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Copyright © 2007 by the American Society of Plant Biologists
